Handheld pneumatic impact tools are commonly used for engraving or removing small amounts of material from jewelry and other fine workpieces, and may even be used in orthopedic and dental surgery. Such tools typically use a pneumatically-driven piston reciprocating in a pneumatic chamber in the tool handle to transmit force to a fixed anvil in contact with a graver tip. The force transmitted to the graver tip through the anvil removes material from the workpiece. Air pressure is supplied from a separate controller through a flexible supply line. Different types of controller are commercially available.
The piston is driven intermittently by air pressure against a return spring to strike the anvil and transmit impact force to the graver in pulses. Since the graver tip is usually fixed in place, the tool moves slightly in the user's hand against the workpiece, or moves the user's hand slightly toward the workpiece.
Pistons for these pneumatic impact tools usually have a larger diameter rear base and a reduced diameter forward striker pin riding inside the return spring. The piston is contained in a pneumatic chamber and the tip of the striker pin strikes an end of the pneumatic chamber, which functions as an anvil.
In my experience, prior pneumatic impact engraving tools used by jewelers tend lack sufficient striking force at slow speeds, possibly due to their relatively fast oscillation rate and light strikers.